Convert CONFIG_BOARD_EARLY_INIT_F to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_EARLY_INIT_F

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/picosam9g45_defconfig b/configs/picosam9g45_defconfig
index 90cc75e..bf6ffc6 100644
--- a/configs/picosam9g45_defconfig
+++ b/configs/picosam9g45_defconfig
@@ -14,6 +14,7 @@
 # CONFIG_CONSOLE_MUX is not set
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot> "